Electrical machinery brush holder



Jan. 21, 1969 G. E. SCHMID ET AL 3,423,618

ELECTRICAL MACHINERY BRUSH HOLDER Sheet Filed April 25, 1966 Jan. 21, 1969 E sc ET AL 3,423,618

ELECTRICAL MACHINERY BRUSH HOLDER Filed April 25, 1956 United States Patent 2 Claims ABSTRACT OF THE DISCLOSURE A brush holder assembly for electrical rotating machinery and having a constant presure coil spring fixed to one end of a removable back plate for urging the brush into contact with the commutator. The back plate also has means at the same end at which the coil plate is secured, which means slidingly holds the back plate captive in the brush holder so that the coil spring can hold the brush upwardly in inoperative position when the back plate has been raised and tilted rearwardly against the stop.

The present invention relates to a brush holder as sembly for electrical rotating machinery, the holder as sembly being of the type having a constant pressure coil spring for urging the brush into contact with the commutator or the like.

Brush holder assemblies of this general character are well known and in some of these prior art devices the spring and the spring back plate to which it is attached are removed completely from the brush holder member when it is desired to remove the brush. In other prior art brush holder assemblies, the spring and its back plate are simply pivoted or shiftable to a brush releasing position but are nevertheless held on the holder member so as to prevent it from being misplaced, dropped or otherwise damaged while the brush itself is being repaired or replaced. This latter type of brush holder assembly is referred to as the captive type and it is to this type that the present invention relates.

When reassembling some of the prior art brush holders, it is necessary to pull or unwind the coiled spring with the finger in order to reset it on top of the brush. Under many circumstances this is very difficult and awkward to do. In other prior art devices, it is necessary to remove the brush completely in order to repair or inspect the commutator, and if the brushes are not carefully removed and laid aside in a safe place, they frequently are dropped, misplaced or otherwise damaged, and it is generally a time consuming task to remove and replace these brushes, particularly if the electrician is working in cramped quarters, or high on an overhead crane. Still other prior art devices of this type are fabricated from many and rather complex and expensive parts and are consequently costly to manufacture and often complicated and diflicult to disassemble or assemble.

Accordingly, the present invention provides a captive type brush holder which eleminates the above shortcomings of the prior art.

The present invention provides an improved, captive type brush holder in which the spring can easily be shifted in or out of brush holding position and can also provide constant brush pressure; the spring can be easily reset on top of the brush by a lever action of the back plate and without the necessity of pulling the spring by hand to a position on the brush. In addition, the spring and back plate arrangement are such that they act to securely hold the brush in a non-operative position in the holder and out of contact with the commutator, making it unnecessary to remove the brush when servicing the commutator.

3,423,618 Patented Jan. 21, 1969 The improved brush holder is particularly simple in construction, utilizing a miniumum number of parts, and is easily and simply disassembled or assembled with only one hand.

These and other objects and advantages of the present invention will appear hereinafter as this disclosure progresses, references being had to the accompanying drawings, in which:

FIGURE 1 is a perspective view of a brush holder embodying the present invention and in the operative position;

FIGURE 2 is a side elevational view of the holder as shown in FIGURE 1;

FIGURE 3 is a view similar to FIGURE 2 but showing the spring and back plate when initially moved from the FIGURE 2 position as when starting to shift them to a non-operative position;

FIGURE 4 is a view similar to FIGURE 3 but showing the spring and plate when moved farther toward a released position;

FIGURE 5 is a view showing the spring and holder in the released position;

FIGURE 6 is a perspective view, generally similar to FIGURE 5, but showing the brush elevated out of contact with the commutator and being held in a hanging position by the spring;

FIGURE 7 is a perspective view of the spring and back plate; and

FIGURE 8 is a perspective view, from above and rear side of the brush holder member and spring support bracket.

Referring in greater detail to the drawings, the brush holder member 1 has a passage 2 in which the carbon brush 3 is slidable against the commutator 4, as shown in FIGURES 1 and 2, or slidable upwardly away from the commutator where it is hung out of the way of the commutator, as shown in FIGURE 6. The brush 3 is electrically connected to member 1 in the conventional way by the flexible cable C.

A spring support bracket 7 is secured by cap screws 6 to one side of the member 1 and forms a guide recess R therewith. It will be noted that the bracket 7 together with member 1 also forms a pair of side slots 12. The bracket includes a laterally or outwardly extending stop 9 and an opening 9a. The "bracket has an internal surface 10 for a purpose that will appear later, and at the top of the bracket is formed a pair of spaced apart, inwardly extending hooks 11.

A self-rewinding coil spring 12 is riveted at one end to a spring back plate 13, and this spring has a coil portion 12a adapted to bear against one end of the brush to resiliently urge the other brush end against the commutator in the known manner.

In many prior art devices, after the brush has been removed and then replaced in member 1, it has been a rather difilcult task to partially uncoil the spring and again position it on top of the brush.

The spring back plate 13 includes an overhanging, hook-shaped handle 14 which terminates in a free end 14a and has an internal surface 14b for purposes that will appear. The plate 13 also includes a pair of oppositely extending, side lugs 16 which, as shown in FIG- URE 2, are adapted to be held retained under the hooks 11 when the spring plate is in the operative position. To free these lugs from hooks 11, as shown in FIGURE 3, the handle is depressed against the bias of the spring, and then moved away slightly from the bracket 7. At its lower end the plate 13 has a pair of oppositely and laterally extending guide projections 18 formed integrally therewith which slide in and are guided and held captive in the adjacent side slots 12.

Operation When it is desired to raise or remove the brush from the operative position as shown in FIGURES l and 2, the handle is depresesd and moved away slightly from the bracket 7, thus freeing the lugs 16 from their hooks, as above mentioned. The self-rewinding spring then tends to pull the handle upwardly, the projections 18 sliding in the guide slots 12 and bearing against member 1 while the lowermost end of the plate 13 slidingly bears against the internal surface 10 of the bracket. Positive control of the plate movement is thus assured. As the plate raises, the spring tries to ride forwardly over the top front corner 19 of the brush, but it is prevented from doing so by the internal surface 14b of the curved handle 14. The free end 14a of the handle extends downwardly sufliciently to hold the spring and preclude it from going over the top corner 19 of the brush until the plate has been raised sufliciently to a point where it can be tilted rearwardly through the opening 9a formed in the bracket. The plate lies at rest on the stop 9, and before the brush is pulled upwardly, the spring assumes the position shown in FIG- URE 5.

It will be noted that the spring is riveted to the lower end of the plate 13 and the latter lies closely adjacent the brush when in the FIGURE position. Thus the spring still overlies a portion of the brush.

To raise the brush from the FIGURE 5 position and hang it out of the way of the commutator as shown in FIGURE 6, the spring is pulled back slightly, that is to say, it is unwound slightly along the plate 13, clearing it from the top of the brush. The brush is then elevated or pulled away from the commutator the desired amount, and the spring then released and permitted to wind up against the side of the brush, holding the latter in the desired clearance position.

When it is desired to return the brush to the operative position against the commutator, it is only necessary to swing the plate upwardly which causes the spring to ride up on the top of the brush. Then the handle is simply pushed down and the lugs 16 locked under the hooks 11.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention:

1. A brush holder assembly for an electrical rotating machine having a commutator comprising, a brush holder member having a passage in which a brush is slidable between a position in which one end of said brush is in engagement with said commutator and a position where said one end is away from said commutator, a bracket secured to said member and formingv a guide recess therewith, said bracket defining an opening and having a generally laterally extending stop adjacent said opening, hook means on said bracket adjacent said openings, a back plate slidable in said recess and having means at one end for slidingly holding it captive in said recess, the other end of said plate terminating in a handle located above said recess and brush, whereby said plate can slide between an operative position in which said one end of said brush is held against said commutator and an inoperative position away from said commutator where said plate is swung through said opening and lays against said stop with said one end of said plate located adjacent said brush, a self-rewinding spring secured to said one end of said plate and having a coil portion abutting against the other end of said brush when said plate is in said operative position, and when said plate is in said inoperative position against said stop then said coil portion bears against a side of said brush to hold the latter in said position away from said commutator.

2. The assembly as defined in claim 1 further characterized in that said handle has a hook-shaped, overhanging portion against which said spring coil portion bears to hold said spring within said handle when said plate is being slid away from said commutator.

References Cited UNITED STATES PATENTS 2,836,745 5/ 1958 Gillie 310-246 2,840,734 6/ 8 Nottelmann 310-246 2,992,344 7/ 19611 Gillie 310-246 ORIS L. RADER, Primary Examiner.

G. NUNEZ, Assistant Examiner.

US. Cl. X.R. 

